Outer Limits 4x4 Board

Just wanting to know if there is any dramas adding a spacer on the inlet side of a turbo to get it to stick out a bit further. worse case maybe need 2 spacers . I realise i need longer threads and a gasket at each mating surface,etc.

Thanks

how far mate?

better off making proper adapter with 2 flanges and a middle section.

You can't space the compressor housing forward, the clearance to the compressor wheel is minimal. If that is what you mean?

Joel

you mean between the exhaust manifold and the turbo? Yes you can, mine is spaced about an inch (t3-t2 adapter)

6.5 rangie wrote:you mean between the exhaust manifold and the turbo? Yes you can, mine is spaced about an inch (t3-t2 adapter)

What he said. I also have a 25mm manifold adaptor for my turbo. Makes no difference to performance.

If you were to get technical, spacing it out would change the band at which torque/boost comes on, as you're changing the length of the runners. It wouldn't be noticed on a 4x4 or most cars for that matter.

Depending on how far you wanted to space it i would brace the turbo, to stop cracking from shock.

berad wrote:If you were to get technical, spacing it out would change the band at which torque/boost comes on, as you're changing the length of the runners. It wouldn't be noticed on a 4x4 or most cars for that matter.

No it wouldn't.
Turbo manifolds don't have tuned lengths, the constantly changing exhaust temperature changes the sonic velocities and makes length tuning impossible.

i need to go a minimum of 14mm. Measured it with old gasket in place.

14mm will give me about 5mm clearance off the starter motor. If i heat wrap the starter might be enough or i can add a bonnet scoop and direct some fresh air to help stop cooking the starter

pongo wrote:i need to go a minimum of 14mm. Measured it with old gasket in place.

14mm will give me about 5mm clearance off the starter motor. If i heat wrap the starter might be enough or i can add a bonnet scoop and direct some fresh air to help stop cooking the starter

A shiney stainless heat shield will give the best protection. It's radiated heat you're mostly concerned about.

KiwiBacon wrote:

berad wrote:If you were to get technical, spacing it out would change the band at which torque/boost comes on, as you're changing the length of the runners. It wouldn't be noticed on a 4x4 or most cars for that matter.

No it wouldn't.
Turbo manifolds don't have tuned lengths, the constantly changing exhaust temperature changes the sonic velocities and makes length tuning impossible.

I didnt say tuned length. i said changing the length of the runners really i should have said the collector as thats what he'd be adding to. .

KiwiBacon wrote:

berad wrote:If you were to get technical, spacing it out would change the band at which torque/boost comes on, as you're changing the length of the runners. It wouldn't be noticed on a 4x4 or most cars for that matter.

No it wouldn't.
Turbo manifolds don't have tuned lengths, the constantly changing exhaust temperature changes the sonic velocities and makes length tuning impossible.

I think a few turbo people would disagree. There shouldn't be any significant difference in exhaust velocities or you would have a serious issue. The formulas are difficult if done correctly as the bend radius has to be calculated in. I think you will find any serious turbo race car or turbo race boat will have tuned length turbo extractors with an efficient collector design.

PGS 4WD wrote:I think a few turbo people would disagree. There shouldn't be any significant difference in exhaust velocities or you would have a serious issue. The formulas are difficult if done correctly as the bend radius has to be calculated in. I think you will find any serious turbo race car or turbo race boat will have tuned length turbo extractors with an efficient collector design.

How do you can tune the length when the sonic velocity (i.e. pulse speed) rapidly and constantly changes?

Factory manifolds are almost all minimum volume type to minimise lag. I'd like to see any you have pictures of which aren't. Race cars and race boats which are turbocharged will be petrol, which often use equal length (but not tuned length) runners. Very different application to the one being discussed.

The formulas for turbo sizing do not include bend radii in the manifold.

The only thing that would need tuned length runners was the f1's when they ran turbos. Altering length of exhaust and inlet altered where the power band was quite a lot.

Anything apart from that is not really needed, there are too many ineffeciencies in the td42 engine to worry about tuned length runners. You would need to be over 250rwkw to warrent them, imho.

We have had 2 vehicles that used the same Garrett in our upgrade, one stock except for turbo and fuel adjustments, the other small tuned length exhaust and an open manifold intercooler, there was lucky to be 5% between them.


Andy